Tube shaping device

ABSTRACT

Two longitudinal tube forming members are dimensioned to fit within the interior of a hollow tube and to impress a predetermined cross-sectional shape on the tube when they are pressed against opposing interior surfaces thereof. The tube forming members are joined together in substantially parallel relationship by a symmetrical toggle mechanism which varies the spacing between the tube forming members in response to the movements of a hydraulic ram. The hydraulic ram is mounted in the middle of the toggle mechanism so as to apply longitudinally balanced forces to the toggle mechanism and thereby to equalize the distribution of forces in the structure when the tube forming members are pressed against opposing interior surfaces of the tube. The upper tube forming member is rigidly attached at one end to a supporting column and the lower tube forming member is slidably attached at one end to the supporting column so that it can be raised and lowered by the toggle mechanism to vary the spacing between the two tube forming members.

United States Patent 1 Jones i 1 3,710,609 [451 Jan. 16, 1973 TUBE SHAPING DEVICE [76] inventor: Cecil H. Jones, 153 West Glencrest Drive, Mankato, Minn. 56001 22 Filedi "oeeso, 1970 [21] Appl. No.: 102,848

[52] US. Cl ..72/392 [51] Int. Cl. ..B21d 31/04 [58] Field of Search ..72/370, 392, 393

[56] References Cited UNITED STATES PATENTS 2,931,416, 4/1960 Krise ..72/393 3,266,285 8/1966 Jensen ..72/393 FOREIGN PATENTS OR APPLICATIONS 887,634 8/1953 Germany ..72/393 Primary Examiner-Lowell A. Larson Attorney -carlsen, Carlsen & Sturm [57 ABSTRACT Two longitudinal tube forming members are dimensioned to fit within the interior of a hollow tube and to impress a predetermined cross-sectional shape on the tube when they are pressed against opposing interior surfaces thereof. The tube forming members are joined together in substantially parallel relationship by a symmetrical toggle mechanism which varies the spacing between the tube forming members in response to the movements of a hydraulic ram. The hydraulicram is mounted in the middle of the. toggle mechanism so as to apply longitudinally balanced forces to the toggle mechanism and thereby to equalize the distribution of forces in the structure when the tube forming members are pressed against opposing interior surfaces of the tube. The upper tube forming member is rigidly attached at one end to a supporting column and the lower tube forming member is slidably attached at one end to the supporting column so that it can be raised and lowered by the toggle mechanism to vary the spacing between the two tube forming members.

10 Claims, 6 Drawing Figures iilIiii.

-| llllll' 'lillilll HHIHH llllill TUBE SHAPING DEVICE BACKGROUND OF THE INVENTION This'invention relates to tube shaping devices which are used to change the cross-sectional shape of hollow tubes by means of expansive forces applied to the in-' I obtained by a hydraulic ram or similar extendable member which was mounted on one end of the expandable tube forming members that made contact with the interior of the tube. The expansive force of the hydraulic ram was transmitted to the expandable tube forming members by means of a toggle mechanism or similar force transmitting and translating mechanism. Since the force was generated at one end of the tube forming .members, however, and .then mechanically transmitted along the length of the tube forming mem bers, the result was an unbalance of forces which not only effected the tubing that was being shaped but also produced undue wear in the moving parts of the device, particularly in applications that required either large expansive forces or relatively large movement of the expandable tube forming members. Accordingly, the principal object of this invention is to provide an improved tube forming device in which the expansive forces are balanced so as to improve the operation of the device and reduce wear due to unbalanced forces.

Additional objects of this inventionare to provide a FIG. 3 is a cross-sectional view taken on the plane 33 of FIG. 1 with the tube forming members and togglemechanisms thereof in their retracted position.

FIG. 4 is a cross-sectional view taken on the plane 3-3 of FIG. 1 with the tube forming members and togglemechanisms thereof in their expanded position.

FIG. 5 is an end view of the embodiment shown in FIGS. 1-4 with the tube forming members-and toggle mechanisms thereof in their retracted position.

FIG. 6 is an end view of the embodiment shown in FIGS. 1-4 with the tube forming members and toggle mechanisms thereof in their expanded position.

DESCRIPTION OF THE INVENTION Referring to the figures, one illustrative embodiment of the invention comprises two longitudinal tube forming members 10 and 12 which are dimensioned to fit within the interior of a hollow tube 14 and to impress a predetermined cross-sectional shape on the tube when they are pressed against opposing interior surfaces thereof, as best shown in FIGS. 2, 5, and 6. The upper member l2'is suspended from the upper tube forming more durable in use than those heretofore known in the art.

SUMMARY OF THE INVENTION In accordance with this invention, it has been found that the above-noted objects can be achieved by providing two longitudinal tube forming members which are joined together in substantially parallel relationship by a symmetrical toggle mechanism which varies the spacing between the tube forming members in response to the movements of a hydraulic ram. The hydraulic ram is mounted in the middle of the toggle mechanism so as to apply longitudinally balanced forces to the toggle mechanism and thereby to equalize the distribution of forces in the structure when the tube forming members are pressed against opposing interior surfaces of a tube. The upper tube forming member is rigidly attached at one end to a supporting column and the lower tube forming member isslidablyattached at one end to the supporting column so that it can be raised and lowered by the toggle mechanism to vary the spacing between the two tube forming members; Other more specific features of the invention are described below in connection with one specific embodiment thereof, as illustrated in the attached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 2 is an elevation view of the embodiment shown I in FIG. 1.

member 10 by a symmetrical array of toggle mechanisms 24, 26, 28, and 30, which varies the spacing between the two tube forming members in response to the movements of a hydraulic ram 32,as best shown in FIGS. 3 and 4. The end of lower tube forming member 12 is adapted to slidably engage a pair of guide rails 34 attached to vertical supporting column 16. The guide rails 34 restrain the end of lower tube forming member 12 so that it will not move longitudinally while it is being raised and lowered by the toggle mechanisms 24-30.

The toggle mechanisms 24-30 are symmetrically disposed with respect to the hydraulic ram 32, which is mounted in the center of the symmetrical disposed toggle mechanisms and coupled thereto in such manner as of toggle mechanism 28 and the piston of hydraulic ram.

32 to'the center of toggle 26, whereby equal and'opposite forces will be applied to the toggles 26 and 28 in response to the application of hydraulic pressure to the hydraulic ram 32. These forces are transmitted to toggles 24 and 30 by means of linkage rods 36 and 38 so that equal and opposite forces will also be applied to toggles 24 and 30. It will be clear to those skilled in the art that more toggle mechanisms could be used if necessary to distributethe forces more evenly along the tube forming members without changing thefundamental. nature of the force linkage mechanism. It will beequally apparent that two'toggle mechanisms would suffice in cases where the tube forming members were extremely short.

The hydraulic fluid for hydraulic ram 32 is drawn from a hydraulic fluid reservoir 36 (FIG. 2') by a hydraulic pump 38 which is driven by an electric motor 40, all of which are mounted on the back of vertical supporting column 16. The hydraulicfluid is coupled through hydraulic tubing tov hydraulic ram 32 via a manually operated hydraulic valve 42 which is attached to the other end of upper tube forming member 10. In one position of hydraulic valve 42, the hydraulic pressure is applied to one side of the piston of hydraulic ram 32 to move it toward the retracted position, and in the other position of hydraulic valve 42, the hydraulic pressure is applied to the other side of the piston to move it toward the expanded position. The hydraulic valve 42 is mounted on the open end of the upper tube forming member for the convenience of the operator in this particular embodiment of the invention. It will be clear to those skilled in the art, however, that the other end of the tube forming member may be more convenient in other embodiments of the invention.

In the operation of this embodiment of the invention, the operator first moves the hydraulic valve 42 to the position that brings the two tube forming members together as shown in FIG. 3, and then slides the unformed tube 14 over the tube forming members 10 and 12. as shown in FIGS. 2 and S. The hydraulic valve 42 is then moved to the other position, which causes the tube forming members 10 and 12 to move away from each other as shown in FIG. 4, thereby pressing against opposing interior surfaces of the tube 14 and changing -its shape as shown in FIG. 6. It will be clear from FIG. 6

that the cross-sectional shape and maximum expansion of the longitudinal tube forming members 10 and I2 is adapted to produce a predetermined cross-sectional shape in the tube 14. In this particular embodiment of the invention, the shaped tubes are used as pontoons for pontoon boats, but it will be clear to those skilled in the art that the disclosed structure can be used to shape tubes for other purposes, and also that different shapes can be achieved by suitable modification of the longitudinal tube forming members.

The principal object of this invention is to provide a tube forming structure in which the expansive forces are balanced during the tube forming operation so as to apply equally distributed forces along the length of the tube and also to minimize wear and misalignment of the mechanism due to unbalanced forces. In general terms, this is achieved by joining the upper and lower tube forming members together by a symmetrical array of toggle mechanisms, placing the hydraulic ram for operating the toggle mechanisms in the center of the array, and connecting the piston of the hydraulic cylinder to one half of the array and the cylinder of the hydraulic ram to the other half of the array.

As best shown in FIGS. 1 and 5, the upper tube forming member 10 is made of two longitudinal side members 44 and 46 which are joined together in spaced parallel relationship by cross members 48. A central ridge 50 is attached to cross members 48 and extends parallel to side members 44 and 46 to produce a substantially V shaped bottom for the pontoon. The lower tube forming member 12 is made of two longitudinal side members 52 and 54 which are joined together in spaced parallel relationship by cross members 56. Each of the cross members 48 has downwardly projecting ears 49 which are adapted to rotatably receive and support one end of a corresponding toggle mechanism. Each of the cross members 56 has upwardly projecting ears 57 which are adapted to rotatably receive and support the other end of a corresponding toggle mechanism.

Each of the toggle mechanisms comprises a pair of upper toggle arms and a matching pair of lower toggle arms which are journalled together at one end to a cross rod and are journalled at their other end to the ears 49 and 57. Since all of the toggle mechanisms are identical in structure, the detailed structure will only be described for the end toggle mechanism 24. Referring to FIGS. 3, 4, and 6, the toggle mechanism 24 contains two upper toggle arms 58 and 60 which are journalled at one end to downwardly projecting ears 49 and at the other end to a cross rod 62. Two lower toggle arms 64 and 66 which are journalled at one end to upwardly projecting ears 57 and at the other end to cross rod 62. Cross rod 62 is journalled to longitudinal arm 36, which is moved back and forth by the piston of hydraulic ram 32 to expand and contract the toggle mechanism as shown in FIGS. 3 and 4. All of the toggle mechanisms are, of course, actuated at the same time, and the resulting expansive force is applied uniformly along the length of the tube forming members due to the spaced, symmetrical arrangement of the toggle mechanisms.

From the foregoing description it will be apparent that this invention provides an improved tube forming device in which the expansive forces are balanced so as to improve the operation of the device and reduce wear due to unbalanced forces. And although this invention has been described in connection with one illustrative embodiment thereof, it should be understood that the invention is by no means limited to the disclosed embodiment, since many modifications can be made in the disclosed structure without altering its fundamental principle of operation. For example, although four toggle mechanisms have been used in the disclosed embodiment, it will be clear that a larger number can be used if desired. Moreover, it will be clear that the toggle mechanisms can be replaced I by equivalent mechanical structures without changing the nature or function of the device. These and many other modifications of the disclosed structure will be apparent to those skilled in the art, and this invention includesall modifications falling within the scope of the following claims.

I claim:

I. A tube shaping device for applying expansive forces to the interior of a hollow tube of semi-rigid material to change the cross-sectional shape of said tube, said tube shaping device comprising two longitudinal tube forming members which are dimensioned to fit within said tube and to bear against opposing interior surfaces thereof, at least two force translating mechanisms coupling said tube forming members together in substantially parallel relationship, said force translating mechanisms being operable to translate a force which is directed parallel to said tube forming members into a force which is directed perpendicular thereto, one of said tube forming members being rigidly attached to a vertical supporting column and the other tube fomiing member is connected to said first mentioned tube forming member by means of said force translating mechanisms, and force generating means mounted between said force translating mechanisms for applying equal and opposite forces thereto for forcing said longitudinal tube forming members against op posing interior surfaces of said tube to change its crosssectional shape.

coupled to the other toggle mechanism, and means for applying hydraulic fluid under pressure to said cylinder to cause relative movement between said piston and said cylinder.

5. A tube shaping device as defined in claim l wherein one of the tube forming members is rigidly at- -tached at one end to a vertical supporting column and the other tube forming member is suspended from the first mentioned longitudinal tube forming member by means of the force translating mechanisms.

6. A tube shaping device'as defined in claim 4 wherein each of said togglemechanisms comprises an.

a lower toggle arm which is pivotally connected at one end to the other longitudinal tube forming member,-

and means pivotally connecting the other ends of the upper and lower toggle arms together.

7. A tube shaping device as defined in claim 6 wherein said means pivotally connecting the other ends of said upper and lower toggle arms together is pivotally connected to said hydraulic ram.

8. A tube shaping device as defined in claim 7 wherein the upper and lower arms of said toggle mechanisms extend at an acute angle to each other, the apex of each acute angle being directed toward said hydraulic ram.

9. A tube shaping device as defined in claim 8 wherein the piston of said hydraulic ram is coupled to the apex of the acute angle formed by the arms of one of said toggle mechanisms and the cylinderof said hydraulic ram is coupled'to the apex of the acute angle formed by the arms of the other of said toggle mechanisms.

10. A tube shaping device as defined in claim 9 and further comprising additional toggle mechanisms coupled between said longitudinal tube forming members,

said additional toggle mechanisms being symmetrically disposed with respect to said hydraulic ram. 

1. A tube shaping device for applying expansive forces to the interior of a hollow tube of semi-rigid material to change the cross-sectional shape of said tube, said tube shaping device comprising two longitudinal tube forming members which are dimensioned to fit within said tube and to bear against opposing interior surfaces thereof, at least two force translating mechanisms coupling said tube forming members together in substantially parallel relationship, said force translating mechanisms being operable to translate a force which is directed parallel to said tube forming members into a force which is directed perpendicular thereto, one of said tube forming members being rigidly attached to a vertical supporting column and the other tube forming member is connected to said first mentioned tube forming member by means of said force translating mechanisms, and force generating means mounted between said force translating mechanisms for applying equal and opposite forces thereto for forcing said longitudinal tube forming members against opposing interior surfaces of said tube to change its cross-sectional shape.
 2. A tube shaping device as defined in claim 1 wherein said force translating mechanisms are symmetrically disposed with respect to said force generating means.
 3. A tube shaping device as defined in claim 2 wherein said force translating mechanisms comprise toggle mechanisms.
 4. A tube shaping device as defined in claim 3 wherein said force generating means comprises a hydraulic ram having a piston which is slidably mounted within a cylinder, said piston being coupled to one of said toggle mechanisms and said cylinder being coupled to the other toggle mechanism, and means for applying hydraulic fluid under pressure to said cylinder to cause relative movement between said piston and said cylinder.
 5. A tube shaping device as defined in claim 1 wherein one of the tube forming members is rigidly attached at one end to a vertical supporting column and the other tube forming member is suspended from the first mentioned longitudinal tube forming member by means of the force translating mechanisms.
 6. A tube shaping device as defined in claim 4 wherein each of said toggle mechanisms comprises an upper toggle arm which is pivotally connected at one end to one of said longitudinal tube forming members, a lower toggle arm which is pivotally connected at one end to the other longitudinal tube forming member, and means pivotally connecting the other ends Of the upper and lower toggle arms together.
 7. A tube shaping device as defined in claim 6 wherein said means pivotally connecting the other ends of said upper and lower toggle arms together is pivotally connected to said hydraulic ram.
 8. A tube shaping device as defined in claim 7 wherein the upper and lower arms of said toggle mechanisms extend at an acute angle to each other, the apex of each acute angle being directed toward said hydraulic ram.
 9. A tube shaping device as defined in claim 8 wherein the piston of said hydraulic ram is coupled to the apex of the acute angle formed by the arms of one of said toggle mechanisms and the cylinder of said hydraulic ram is coupled to the apex of the acute angle formed by the arms of the other of said toggle mechanisms.
 10. A tube shaping device as defined in claim 9 and further comprising additional toggle mechanisms coupled between said longitudinal tube forming members, said additional toggle mechanisms being symmetrically disposed with respect to said hydraulic ram. 